Can't access control ID in code behind

Problem is you might have multiple aspx files with codefile in page directive points to same codebehind file.
It expects the same control to exists in all the aspx file linked to same code behind and thus throwing compilation error.

I had the same problem today and in my case the solution was:

- Go to: `C:\Users\lenovo\AppData\Local\Temp\Temporary ASP.NET Files\`
- Delete the `Temporary ASP.NET Files` folder.

**Check the namespace in all three files**. Sometimes there is a discrepancy between the namespace name in the designer.cs file and the other two files. Be sure to check that name space name match in all three files

Just change the inherit property under page tag

<% Page inherit = "Project_Name.otherform"
change it to

<% Page inherit = "Project_Name.YourForm"
And you will see in form2.aspx.desginer.cs the class name is also changed and corrected.

**Let Me Explain:**
Let's Say you have 2 web forms test1.aspx and test2.aspx. You copied some piece of code from test1.aspx to test2.aspx, your test2.aspx file will use <% page tag as:

<% Page inherit = "Project_Name.test1"
which was supposed to be as:

<% Page inherit = "Project_Name.test2"
because of which your test2.aspx.designer.cs class name will be automatically changed to same as test1.aspx.designer.cs as it is a system generated file and you will be unable to use your control IDs.

After correcting your inherit property, save and Open test2.aspx.designer.cs to verify and you will see in that the class name is also changed.
it will be like:


public partial class test1
{
...

Changed in to

public partial class test2
{
...

Thanks me later ;)